1. Field of the Invention
The present invention relates to a utilization method for a plurality of Redundant Array of Independent Disks (RAID) systems and data storage system thereof, and more particularly, to a method for a plurality of RAID systems and data storage system.
2. Description of the Prior Art
A redundant array of independent disks (RAID) system is a storage technology that combines a number of disks into a large disk group, where information is stored dispersedly in the disks, making the storage efficiency greater than stored in one disk. RAID systems are classified into a number of RAID levels, where RAID 0 system, RAID 1 system, RAID 0+1 system and RAID 5 system are most often used. Except RAID 0 system, the other RAID systems provide various forms of redundancy mechanisms. As such, when a disk fails, data stored in the other disks are utilized for recovering damaged data by logical operations, and writing the recovered data onto a hot spare disk, so as to replace the failed disk.
Please refer to FIG. 1, which is a schematic diagram of a known RAID system 100. The RAID system 100 includes a RAID system server 102, disks HD_1-HD_n, and a hot spare disk HSD. In operation of the RAID system 100, when a disk HD_i from the disks HD_1-HD_n fails, the hot spare disk HSD can replace the failed disk HD_i. That is, if data in the failed disk HD_i can be recovered by data stored in the other disks, recovered data are written on the hot spare disk HSD replacing the failed disk HD_i. By such method, the failed disk HD_i can be changed to a new disk.
From the above mentioned, the RAID system 100 can secure data integrity by utilizing a hot spare disk HSD. Generally, a RAID system includes at lease an independent hot spare disk; that is, multiple RAID systems have to deploy different hot spare disks. For example, if there are two RAID systems and only one hot spare disk, only one RAID system can use this hot spare disk. When a disk in the other RAID system fails, the data in the failed disk can not be recovered. Therefore, hot spare disks which can not be shared for different RAID systems may cause inconvenience of usage, and may increase risk of unrecoverable data.